1. Field of the Invention
The invention is in the field of producing an optimized cooler expander waveform to improve the coefficient of performance of cryogenic coolers.
2. Description of the Prior Art
Cryogenic coolers are inefficient at temperatures below 100.degree. K. Many attempts have been made to improve the efficiency down to and below liquid nitrogen temperatures. At 10.degree. K., the problem is even worse since heat exchange materials operate very poorly at that temperature. The Stirling cycle has achieved the highest efficiency cooler operations. However, further improvements are needed to miniaturize these cryogenic coolers to improve the coefficient of performance (COP), i.e. the watts input power to watts output power, at the very low temperatures. Both the compressor and displacer in either the integral or split free displacer Stirling cycle cooler are sinusoidal in motion. Thermodynamically, the sinusoidal wave is not the most efficient waveform to use.